SUMMER SCIENCE SNIPPETS 5 - a day at the beach

A DAY AT THE BEACH
I love summer especially once the schools have broken up.
I really enjoy being outside, wearing lighter clothes and being by the sea. 
Do you love the smell of the sea?

The smell of the sea is so evocative wherever you are on holiday and for many of us is that childhood memory.....

One of the first things you notice when you arrive is that amazing smell. There is nothing quite like the smell of the sea...... salty, clean, fresh, sandy.........We often think the sea air is healthier for us and of course so bracing!

Did you know that distinctive smell has quite a bit to do with seaweed and decay......It is a sulphurous smell produced seaweed begins to break down and die.........

It is actually hydrogen sulphide produced anaerobically, which is toxic but not in the small quantities you find at the edge of the sea.
However you can also smell that amazing mix of salty water and sulphur tang when you are on a boat so it can't all be seaweed.
The oceans are full of minute phytoplankton and algae which contain and produce Dimethylsulphoniopropionate (!) DMSP used to regulate osmotic pressure in cells.
This compound can be broken down by the cells and also by bacteria giving DMS and this has a very distinct smell - that we associate with oceans.

So a day on the beach maybe wandering along the shoreline smelling the sea is a real science lesson!

While on that wander you might find a washed up jellyfish.

There are more and more jellyfish on our beaches and of course abroad. So there you are splashing around and suddenly you feel a stinging hot pain....yes you've brushed up against a jellyfish or tentacle portion in the water.

The harpoon like cells penetrate your skin easily and inject venom which is designed to paralyse and kill fish and depending on the species will raise a painful welt, blister or make you very ill indeed and could kill you.

However before we all race off the beaches - the sting of most jellyfish found around British water is painful but not lethal.

So having seen that episode of Friends you run off to find someone to pee on you? Well no - because pouring fresh water - including urine - onto a jellyfish sting releases even more venom so experts suggest remove all trace of the tentacle and then  rinse in plenty of salty water and very recent research suggest that hot salty water is best. ( not too sure where you would find hot salty water on a beach!)

 Have I put you off going in the water? Why not stay on the beach and build a sandcastle instead!

My girls loved building sandcastles and digging very large holes with their dad - we even bought a shaped bucket to help us!

Amazingly there are people who spend their time making sand structures and there is quite an art (and some science) to it. A quick search online gives a huge amount of information about how to build the perfect sandcastle.

Here is an extract from a book Sandcastles Made Simple by Lucinda Wierenga, published by Stewart, Tabori & Chang

The list of ingredients for creating a simple sandcastle is short: sand, water and a few digging and carving tools. But that is only the start.......Sand - The first and most important thing you need to know about sand is that you can't do a thing with it unless it's wet. When you add water to grains of sand, the liquid forms "bridges" that connect the granules to one another. This is why damp sand sticks together, so you can shape and carve it.

Apparently the ideal method of building involves Mix Scoop Plop Jiggle and almost as important as understanding how to jiggle is knowing when to stop. 

When the sand has stopped flowing, further jiggling will form cracks in your structure. Don't jiggle sand that has already settled into place.

Have I whetted your appetite for more about sandcastles? There is a whole blog posting about it from 2015 - you can find it here:https://sueskimo.blogspot.com/2015/06/summer-science-snippets-3.html

SUMMER SCIENCE SNIPPETS 3

SANDCASTLES

There is something very British about a bucket and spade holiday.

Memories of sandwiches with real sand crunching between your teeth, struggling to get out of that wet swimming costume in one of those home made  towelling tent things - come on I am not the only one who had one surely!!

As a child we often went to Swanage on the Dorset coast and sometimes travelled along to Weymouth where the large sandy beach is a mecca for makers of amazing sandcastles which they create at the start of the season and paint so they last all summer.

Of course most dads thought they could do just as well....mine used to create cars for us to sit in and also huge holes which I seemed to be forever trying to get out of.

My two girls loved making sandcastles with their dad - and as we holidayed in Wales it was easy to see the real thing to model from.
I think we even bought a castle shaped mould - which is cheating really.

Amazingly there is a whole community of sandcastle artists and a huge amount of research goes into what actually makes the perfect model - what sort of sand, how much water, what height and so on.

So here is a little of that knowledge for you to see if it improves your building.

Of course you don't need a beach - a sandpit will work too

You can find a very scientific article here:
http://www.nature.com/srep/2012/120802/srep00549/full/srep00549.html

Here is a great extract about how to create sandcastles from
Sandcastles Made Simple by Lucinda Wierenga, published by Stewart, Tabori & Chang

The list of ingredients for creating a simple sandcastle is short: sand, water and a few digging and carving tools. But that is only the start.......

Sand - The first and most important thing you need to know about sand is that you can't do a thing with it unless it's wet. When you add water to grains of sand, the liquid forms "bridges" that connect the granules to one another. This is why damp sand sticks together, so you can shape and carve it.
Packing down or "tamping" wet sand drains more water more quickly, creating even shorter bridges and an even more solid clump. Sand that has been compacted in this way can be subjected to extreme carving.

Water 
1 Use lots of water. Dry sand in its natural state is lazy stuff. It wants to lie down and spread out into all sorts of nooks and crannies. The good news is that as long as you keep gravity working for you, there is really no way to add too much water. Which brings us to our second rule.

2 Let it drain. If you've ever tried to make the base of a sandcastle by filling a plastic bucket with wet sand and then trying to unmould it, you've seen how important this rule is. With no place for the excess water to drain off, the sand makes a sucking, sticking, vacuum seal with the plastic and it becomes difficult, if not impossible, to remove the bucket.
This is why successful sand sculptors do not use plastic buckets or other closed moulds but build their shapes by stacking handfuls of wet sand or by tamping it down in a topless and bottomless form.

3 Compact the wet sand to form structures. "Pounding sand into submission" is an intuitive and time-honoured method of strengthening and tightening those bridges that hold the grains together. You can use your hands or feet, or even a tamper, to compact wet sand.

3. The building methods

Soft-packing

Soft-packing is how the majority of the uninitiated approach sand.
 Mound up a big pile of sand and stabilise the pile. Using the long handle of your shovel, poke a lot of deep holes into the pile then pour buckets of water into the holes. Stomp on the pile until it feels very solid beneath you. If necessary, go back and poke more holes and add more water.
Pack and shape. Working from the tallest element in your composition, pack the shape with your hands until it feels stable. Take handfuls of moist sand, push them into place and roughly shape them.
Carve and smooth. Using your smoothing tool, smooth and define the elements of your composition. Moisten as necessary. The longer you work on your composition, the more your sand sculpture will dry out – you must keep it moist.You need to keep pushing and smoothing.

Hand-stacking

When you're tired of crawling around a soft-packed sculpture on your hands and knees, you will be ready to try hand-stacking. It takes practice but once you master the mix-scoop-plop-flatten-jiggle move, you'll be building the best castles on the beach. The method is just a modified dribble technique using larger handfuls of sand – very large, very wet handfuls.
Hand-stacking involves scooping out handfuls of wet sand and helping them settle into each other in order to form structures. It's the only building technique in which you mix the sand and water in advance. With soft-packing, you start moulding with dry sand and then add water.
The most difficult aspect of hand-stacking is that it's less intuitive than soft-packing; many people have an instinctual urge to pound the sand into submission. Hand-stacking is a great way to involve the whole family in a sand-sculpture project, with duties evenly divided between "stackers" and "carvers".

Mix Scoop Plop Jiggle

You will soon find that big, fat things are easier to carve then little, skinny things, so build big. To do this, you need big handfuls of sand. You do not need big hands to get big handfuls if you scoop properly.
With one smooth, swift motion (so that you don't lose too much water), plop the double handful of sand on to your base. There may be a bit of "pouring", but a common error to avoid is the "slam dunk". The taller and more delicate your structure is, the more gently you should plop. If you are building a tower, keep your hands on top of the sand; if you are building a wall, your hands will go directly to the sides.
Jiggle. Very gently, jiggle the new pile of sand. The common urge is to force this to happen by pounding, packing and pummelling the sand into compliance. Resist. Instead of using brute force, jiggle or vibrate the sand, helping it to settle evenly on to the layer beneath. Wet sand wants to flow downwards, and as long as you keep it moving, it will continue to settle in on itself, becoming denser and filling in spaces.

Almost as important as understanding how to jiggle is knowing when to stop. When the sand has stopped flowing, further jiggling will form cracks in your structure. Don't jiggle sand that has already settled into place.

There is so much more info on the internet so do some research and find out the fascinating science of sandcastles and maybe you will be building amazing structures like this.....

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